Intra-body communications is a short range communication solution suitable for Body Area Networks wherein the human body is used as the transmission medium. Currently, some studies have succeeded to transmit and receive simple information. However, intra-body communications could also provide broadband applications such as video streaming which will need high data rates. In this paper, firstly we investigate the propagation characteristics of the human body as a conductor of radio frequency signals. Afterwards, we evaluate five digital modulation schemes for intra-body communications. In the experiments, several distances between transmitter and receiver, symbol rates and frequency carriers are considered to investigate the optimal modulation scheme and the maximum transmission rate achievable. Constellation and eye diagrams and error vector magnitude are the performance parameters measured to evaluate the modulation accuracy.